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Tag Archives: Argument

When creating a Java application we might want to pass a couple of parameters to our program. To get the parameters passed from the command line we can read it from the main(String[] args) method arguments.

To make a class executable we need to create a main() method with the following signatures:

public static void main(String[] args) {
}

This method takes an array of String as the parameter. This array is the parameters that we pass to the program in the command line.

package org.kodejava.example.basic;
public class ArgumentParsingExample {
public static void main(String[] args) {
for (int i = 0; i < args.length; i++) {
System.out.println("Argument " + (i + 1) + " = " +
args[i]);
}
// If you want to check if the number of supplied parameters
// meet the program requirement you can check the size of
// the arguments array.
if (args.length < 3) {
System.out.println(
"You must call the program as follow:");
System.out.println(
"java org.kodejava.example.basic.ArgumentParsingExample arg1 arg2 arg3");
// Exit from the program with an error status, for
// instance we return -1 to indicate that this program
// exit abnormally
System.exit(-1);
}
System.out.println("Hello, Welcome!");
}
}

When we try to run the program without argument we will see the following message:

$ java org.kodejava.example.basic.ArgumentParsingExample
You must call the program as follow:
java org.kodejava.example.basic.ArgumentParsingExample arg1 arg2 arg3